Couplings adapted for engagement with the outer surface of a polymeric pipe are well known. The couplings generally include a sub-assembly of a compression sleeve, a resilient gasket ring permanently attached to the inner end of the compression sleeve, a gripping member, and a nut. The gasket ring encounters an abutment in a socket in the body as the nut is tightened, and further tightening of the nut radially compresses the gripping member so that its inwardly directed barbed projections engage the outer surface of a pipe to which the coupling is attached. The end of the pipe is freely insertable through the gripping member and sleeve and into the socket in the body. There are also provided abutment surfaces within the body coupling and the nut that abut inner and outer surfaces of a flange outstanding from the outer end of the compression sleeve.
These couplings have proven to be very successful, both technically and commercially and have achieved great success.
A practical problem that is frequently encountered with such couplings is that the coupling is too long for particular applications, such as homes and meter boxes. However, the nature of plastic couplings is such that common knowledge assumes that they require length to provide for the strength needed.
Thus, in applications where size is important metal fittings have been used whose strength properties allows them to be much shorter. These are however significantly more expensive than moulded plastic couplings.
It is therefore an object of the present invention to provide for a pipe coupling that overcomes at least some of the abovementioned problems or provides the public with a useful alternative, by providing a plastic coupling that is significantly shorter than hitherto known. This results in significant cost savings in that less plastic raw material is needed. Other advantages of shorter plastic couplings relate to issues of stocking, warehousing, transportation, and weight.